Session 1B — Lectures by Fellows/Associates

Umesh Waghmare, JNCASR, Bengaluru

Room temperature magnetic skyrmion bubbles in centrosymmetric magnets View Presentation

Magnetic skyrmions/antiskyrmions are topologically nontrivial chiral spin textures, whose topological protection helps them to move in lower cut-off current by avoiding defects, hence considered as potential candidates for high density racetrack memory devices. In general, the competing Heisenberg exchange and the Dzyaloshinskii-Moriya interaction (DMI) in noncentrosymmetric systems gives rise to the formation of skyrmions/antiskyrmions . Recently skyrmion like spin textures have also been found in centrosymmetric magnets with uniaxial magnetocrystalline anisotropy (UMA). Competing dipolar interaction and UMA is the fundamental mechanism for the stabilization of skyrmions in these materials. Here, we explore room temperature hexagonal skyrmion lattice in a new centrosymmetric kagome ferromagnet using Lorentz transmission electron microscopy (LTEM). The stripe domain like magnetic ground state transforms into skyrmion lattice with increasing magnetic field applied along the c- axis over a wide range of temperature. Existence of skyrmions with opposite helicities are observed due to the degenerate energy state of both skyrmions in the centrosymmetric magnets. A switching mechanism of chiral skyrmion (topological number ± 1) to non-chiral type II bubble (topological number 0) is also demonstrated by applying a nonzero in plane magnetic field excitation.